Process of treating native cellulose with a liquid alkylenepolyamine and a textile resin



United States. l atentj' O ce.

{PROCESS OF TREATING NATIVE CELLULOSE WITH A LIQUID ALKYLENEPOLYAMINE AND A TEXTILE RESIN No Drawing. Filed Mar. 4, 1955, Ser. No. 492,318

1 Claim. (Cl. 8-1155) (Granted under Title 35, US. Code (1952), see. 266) A non-exclusive, irrevocable, royalty-free license in the invention herein described, throughout the world for all purposes of the United States Government, with the power to grant sublicenses forsuch purposes, is hereby granted to the Government of the United States of America.

This invention relates to treat-ing native cellulose fibers; toreduce their crystallinity and/ or to distend andenlarge their crystalline unit cells.

' Native cellulose fibers have a crystal form of cellulose I and are composed of two phases or modifications. One of the phasesis the relatively dense, brittle and inert crystalline phase, and the other is the less dense, more flexible and reactive, amorphous phase. It is known that treatments which reduce the relatively high crystallinity (about 85 to 90% in the case of cotton fibers) of the native cellulose fibers, without chemically degrading the.

fibers or changing their crystal form, improve the desirability and utility of the fibers.

It was found that while most amines exert little decrystallizing effect upon native cellulose fibers, treating the fibers with anhydrous methyl or ethylamine, or with a mixture of either of those amines with anhydrous primary alkylamines containing 6 or 7 carbon atoms, materially reduces the crystallinity of the fibers. A process of producing undegraded native cellulose fibers of reduced crystallinity by such a treatment is described in US. Patent No. 2,580,491.

-We have now discovered that the properties of native cellulose fibers can similarly be improved by atreatment with a liquid alkylenepolyamine, which need not be conducted under anhydrous conditions. In addition, we have discovered that by a treatment with such an amine, the native cellulose fibers can be converted to a novel and particularly useful form of'liquid-free permanently distended fibers.

One object of the present invention is to provide a process of producing undegraded nativecellulose fibers of reduced crystallinity, comparable to those obtainable by. the process of US. Patent No. 2,580,491,. by means of a simple treatment in'which anhydrous conditions need not be maintained. Another object of the invention isto provide liquid-free distended native cellulose fibers in which unit cells are distended by the presence of molecules of analkylenepolyarnine held between glucose units in an alkylenepolyamine-cellulose complex in which the polyamine is resistant toward extraction by non-polar organic liquids but is susceptible to extraction with hot water or polar organic liquids that are inert toward cellulose,

In general, the process in accordance with this invention comprises contacting native cellulose fibers with a liquid of the group consisting of liquid alkylenepolyamines and solutions consisting essentially of from about 55 to 95- weight percent of liquid alkylenepolyamines and from about to 45 weight percent'of liquids which are unreactive toward the alkylenepolyamines and cellulose, until an alkylenepolyamine-cel-lulose complex is formed, and then with a liquid.

2,955,014 Patented Oct. 4, 19 60 freeing the so-treated fibers from unattached alkylenepolyamine.

The process of the present invention can be employed in the treatment of native cellulose fibers such as cotton, linen," ramie, and the like vegetable fibers. Such fibers can be treated in the form of free fibers, sliver, yarn, threads, fabrics and the like. The treatment of vegetable textile fibers in the form of yarns and threads is preferred.

Illustrative examples of liquid alkylenepolyamines which can be used in the present process include ethylenediamine, tetramethylenediamine, diethylenetriamine, hexamethylenediamine, and the like. Alkylenepolyamines containing from about 2 to 6 carbon atoms are preferred. These may also contain from about 0 to 5% by weight of water and/ or other amines.

Treatment of the fibers with the polyamine can be conducted in any apparatus adapted for contacting solids It can be conducted under subatrnospheric or superatmospheric pressure; but the use of normal atmospheric pressure is preferred.

The temperature at which the fibers are contacted with the alkylenepolyamine can be varied widely; but, in general, the use of temperatures of from about 20 to 50 C. A

is preferred.

The alkylenepolyamine with which the fibers are contacted can be diluted with up to about 50% of its weight of substantially any liquid which is an'unreactive solvent for the polyamineand is unreactive toward cellulose. Illustrative examples of suitable liquid diluents include polar liquids, which term is used to refer to liquids having a relatively high dielectric constant which yield hydrogen-bonded complexes of noticeable strength with alky-lenepolyamines, such as: water; water-soluble ketones such as acetone, and the like. 'Also suitable are nonpolar organic liquids including hydrocarbons such as the hexanes, the pentanes, and the like; and symmetrically halogenated hydrocarbons such as carbon tetrachloride, and the like.

, T-he fiberswhich have been contacted with the alkylenepolyamine-containing liquid can be freed of the unattached'polyamine by a mechanical removal employing the usual procedures and apparatus for removing a liquid from textile fibers. The use of squeeze rolls or centrifuges is preferred.

' Where it is desired to produce substantially undegraded native cellulose fibers of reduced crystallinity, the fibers are preferably immersed in a polar liquid solution of an alky-lenepolyamine, such as a water-diluted alkylenepolyamine containing at least about 60% by weight of the polyamine. The use of such solutions containing from about 70 to 96% polyamine, and the freeing of the contacted fibers of the polyamine by mechanically removing part of the polyamine and extracting the remainder with a low boiling polar liquid which is inert toward cellulose is preferred. The use of acetone as the polar extracting liquid is particularly preferred. The extent of the reduction of crystallinity depends upon the' length of time for which the fibers are contacted with the polyamine.

The X-ray diffraction patterns of cellulose fibers which have been treated with polyamine solutions to produce polyaminedecrystallized fibers are those of cellulose I; but the heights of the characteristic diffraction peaks are much reduced, indicating reduced crystallinities. Crystallite size in a polyamine-treated decreases from about 220 glucose units (for the untreated cotton) to about glucose units. The polyamine-treated cellulose exhibits an increased moisture regain as well as increased water retention or imbibition. Tensile tests made on polyamine-treated yarns and cords show that the breaking strength has not been significantly changed, but the percent elongation at-break has been increased, resulting in increased toughness. Determinations of twist show that the treatment causes no significant change in the twist of a yarn.

Where it is'desired to produce liquid-free distended native cellulose fibers in which the unit cells remain distended due to an alkylenepolyamine-cellulose complex, the cellulose fibers are preferably immersed in a substantially pure polyamine. In general, the formation of polyamine-cellulose complex is completed in about 4 hours. The fibers are preferably freed of unattached polyamine by mechanically removing part of the polyamine and evaporating the remainder of the unattached polya-mine. The evaporation of the polyamine is preferably conducted under a reduced pressure. A pressure of less than about millimeters of mercury is preferred.

Liquid-free distended native cellulose fibers in which unit cells are distended by alkylenepolyamine-cellulose complexes, are characterized by a wooly handle i.e., springiness with a warm feel. The cross-sectional area of ethylenediamine distended cotton fibers is about 40% greater than that of the original fibers. X-ray diffraction analyses reveals that the liquid-free distended fibers exhibit the interferences characteristic of the ethylenediamine-cellulose complex which have heretofore been observed only in fibers that were wet with liquid ethylene diamine. An extremely rapid rate of hydrolysis in the presence of hot aqueous acid is one indication of the enhanced reactivity of the polyamine distended fibers. The crystallite length of the distended fibers is short; that of distended cotton fibers being about 100 glucose units, as compared to 225 for the native fibers. The greatly increased interplanar distances of the distended fibers make it easy for dyes and other fiber impregnants that are applied dissolved to penetrate into the crystallite region where they become securely held by a collapse of the distended structure that occurs when the dyestutf solvent is removed. This trapping of the dyestuffs within the crystalline region tends to produce dyed cottons which are fast toward laundering and tends to enable the fibers to take up more dyestuff, resulting in deeper shades.

The presence of the alkylenepolyamine molecules held within the cellulose fiber by hydrogen bond-type linkages renders the distended fibers susceptible to the production of alkylenepolyamine derivatives in situ within the fibers. Such reactions can be accomplished by contacting the distended fibers with a non-polar organic liquid solution, such as a hexane or carbon tetrachloride solution of a reactant capable of reacting with an alkylenepolyamine.

The following examples, which are not to be considered as limiting, illustrate details of the production of substantially undegra-ded cellulose fibers of reduced crystallinity which are free of non-cellulosic components and the production of liquid-free cellulose fibers in which the unit cells are distended by the presence of alkylenepolyamine-cellulose complexes.

EXAMPLE 1 Decrystallization of cotton cellulose with alkylenepolyamines Air-dry kiered cotton singles yarn g.) was immersed in 300 ml. of 96% ethylenediamine, under a nitrogen atmosphere. After a 4-hour immersion, the major portion of the liquid 'diamine was expelled from the reaction vessel by nitrogen pressure. The diamine-wet cotton was thoroughly washed with acetone and finally extracted with acetone to remove the remaining ethylene; diamine.

Examination of the air-dry product by X-ray diffrac-' tion methods indicated that a considerable reduction in crystallinity has been obtained and that the crystal line modification of the remaining crystalline regions was still that of native cellulose (cellulose l). The size of the crystallites was found to have been largely reduced from an original valueof 220 glucose units for the untreated cotton to 116 for the decrystallized product.

EXAMPLE 2 Twenty gram skeins of air-dry kiered cotton yarn were treated as in Example ;1 -w-ith 300 ml. of aqueous solutions of ethylenediamine of the following concentra tionsE -60%, 70%, and I X-r-ay- Grammars oft-he products indi ated that the cotton treated with the 60% ethylenediamine had been little affected. Considerable decrystalliznation was effected y h wo igh r. n e rati ns. fi. effec of. these- Solutions on the crystallinity was confirmed from crystallinity determinations by a chemical method basedon the rate of hydrolysis of the treated cottons by hot, mineral acid] According 'to this method the sample treated; with the 60% ethylenediamine solution was 66% crystalline while the other two treated cottons were 40-45% crystalline. The length of the crystallites in the cotton treated with the 60% solution was found to be 172 glucose units while the more concentrated. solutions of the .diamine both reduced the crystallite length to 114-116 glucose units.

I EXAMPLE3 Alkylelnepolyamine-distended cotton fibers Air-dry kiered cotton yarn (20 g.) was treated with 300 ml. of 98% ethylenediamine (containing about 2% of water) for4 hours at 20 C. under a nitrogen atmos:

'- boiling water surrounding the reaction vessel. The product soobtained was dry to the touch and had only a slight odor of the diarnine although it contained 17.3% of ethylenediamine Examination of this product by X-ray diffraction methods indicated the formation of a cellulose-ethylenedi amine complex with greatly distended interplanar spacings in the crystalline regions. The 101 interplanar spacing in the complex is 11.37 A. as compared to 6.03 A. for this same spacing in untreated cotton.

EXAMPLE 4 Twenty grams of air-dry kiered cotton yarn was treated with 300ml. of 97% ethylendiaminetcontaining about 3% of water) exactly as in Example 3. The diamine content of this yarn after vacuum distillation was l9.7%.- The stability of the diamine complex towards solvents was determined by extracting 1 g. samples of the yarn for 4 hours. with 200 ml. each of the following solvents (the extractions were made in Soxhlet extractors at the boiling point of the respective solvents):

Hexane Methyl ethyl ketone Carbon tetrachloride Isopropyl alcohol chloroform Methyl n-propyl ketone Ethyl acetate Methyl isobutyl ketone Diethylketone Methyl alcohol Acetone Water yarns indicated that the cross section of the dry fibers distillation at 8 mm. pressure.

' containing 19.7% ethylenediamine was 40% greaterthan for untreated fibers.

EXAMPLE 5 the receptivity of the dye was considerably greater for the complex as compared with the untreated cotton.

EXAMPLE 6 A batch of diamine-distended yarns containing 21.6% ethylenediamine, was prepared exactly as in Example 3 from kier-boiled, cotton singles yarns. The tensile data obtained on the treated yarns as compared with the untreated control yarn are summarized below:

I Air-dry kiered cotton yarn (16.5 g.) was immersed in 340 g. of anhydrous hexamethylenediamine (HMDA) at 50" C. under a nitrogen atmosphere. After 4 hours the liquid hexamethylenediamine was drained off. Portions of the remaining liquid diamine were removed by vacuum The vacuum distillation was continued until the yarn in the flask appeared to be free of excess diarnine. n cooling and examination the yarn was found to be encrusted with a coating of solidified hexamethylenediamine. To remove the remaining excess diamine, the treated yarn was extracted for 4 hours at the boiling point with n-hexane. After air-drying the skeins of yarn were perfectly dry to the touch and had no odor of the hexamethylenediamine. The treated skeins were found to contain 29.2% HMDA.

X-ray examination of this material indicated that a new cellulose-complex had been obtained with greatly expanded interplanar spacings in the crystalline regions. The interplan'ar spacing for the HMDA-cellulose complex was found to be 15.5 A. as compared with 6.03 A. in untreated cotton.

Tensile data on the yarn containing the HMDA-cellulose complex together with that of the control yarn are summarized below:

Yarn containing HMDA- cellulose complex Control Yarn Conditioned Not condi- 24 hours tioned Yarn Number (Grex) 466. 5 469. 7 369. 7 Mean .Break Strength (Grams 573. 5:1:15. 6 567. 5:1:12. 8 394. 75:8. 9 Tenacity (Grarn/Grex) 1. 229 1. 208 1. 067 Mean Elongation at Break (Percent) 11. 45:. 5 12. 2:1: 5 7. 45:. 2 Mean Elastic Recovery (Percent) 18. 3:1:1. 5 27. 3:1:1. 6

A microscopic examination of fibers from the treated yarns indicated that the cross-sectional area is 62% greater than for the untreated fibers.

assau t Dye receptivity tests were run on skeins of the HMDA= cellulose complex using the same three dyes listed in Example 5. The same eflect was observed here as with the ethylenediamine-cellulose complex, except to a greater degree. In all cases the yarn containing the HMDA- cellulose complex dyed to a much deeper and brighter shade thandid the control yarn.

f I EXAMPLE 8 Air-dry kiered cotton yarn (20.5 g.) was-treatedwith 400 ml. of redistilled diethylenetriamine (DETA) (98.5%

-triarnine"containing 1.5% of water). 'The excess liquid :triamine wasdrained oi after a 4-hour period and most ofthe'remaining excess triamine was removed by vacuum evaporation at 5 mm. pressure. The vacuumdistillation was continued overnight. The treated cotton was completely dry to the touch and had only a slight odor of the amine. Electrometric titration of a water extract of the treated cotton indicated a triamine content of 36.7%.

X-ray examination of this product indicated that a new triamine-cellulose complex was formed. The X-ray diffraction data show that the DETA-cellulose complex possesses interplanar spacings similar to those of the ethylenediamine-cellulose complex described in Example 3.

Tensile tests of the DETA-cellulose complex showed that there was practically no change in tenacity of the treated yarn relative to the control, but elongation increased 56% and elastic recovery decreased 24%.

A decrystallization which produces substantially undegraded native cellulose fibers of reduced crystallinity changes the fiber properties in a way that cooperates advantageously with the changes brought about by impregnating fibers with a resin. Numerous processes of treating textile fibers with resins are known to impart desirable properties such as wrinkle resistance, shrink resistance, water repellency, flame resistance and the like. Typical textile treating resins include the aminoplast resins such as polymethylolmelamines, poly(dimethylolethylene urea), the melamine and/ or urea-formaldehyde polymers; alkyd'resins such as the polyesters of polyhydric alcohols with maleic acid and the like acids; polyethers such as the polyethers produced by reacting an epihalohydrin with a polyhydric alcohol; and the methylol phosphorus polymers such as those described in US. Patent No. 2,668,096 and copendin-g patent application Serial No. 378,437 filed September 3, 1953. While treating textiles with such resins produced one or more of the indicated advantageous efiects, a resin treatment is characteristically accompanied by an undesirable reduction in the strength of the textile fibers. However, a combination of a decrystallization treatment with the resin treatment imparts the desired efiects of the resin treatment and results in a reduction in strength which is materially less than that caused by the resin treatment of the native fibers. A process of imparting the advantageous efliects of a resin treatment to native cellulose fibers, without materially reducing the strength of the fibers, com-prises, decrystallizing the fibers by a process which produces substantially undegraded native cellulose fibers of reduced crystallinity, and impregnating the decrystallized fibers with the resin.

EXAMPLE 9 Resin treatment of decrystallized cotton cellulose Cotton singles yarn having the crystalline modification and the crystal size of the decrystallized cotton yarns of Examples 1 and 2 were produced by the decrystallization process of US. Patent No. 2,580,491.

Samples of both the decrystallized yarn and the nudecrystallized native yarns were padded, to a dry pickup of about 8%, with a precondensate of a modified urea formaldehyde resin. The resin treatment imparted a loss of about 48% breaking strength to the native cotton 7 yarns; but it imparted a loss of only about 36% to the decrystallized yarns,

-'Precg'ntrrlensates of three ketone formaldehyde resins, onea comr'nercial product, were also applied to native and .c lecrystallizedv yarns, to a dry picklip of about 10%. These resin treatments imparted strength losses of 35- '48%"to the native cotton yarns; but imparted losses of only 10-30% to the decrystallized yarns.

In each case the resin-treated decrystallized yarns exhibited an elongation which was greater than that of the native vyarns. H

We claim: 1

A process of.producingresin-impregnated. native cellulose fibers without materially reducing their strength which comprises treating native cellulose fibers witha ethylenediarnine, tetramethylenedian ine, diethylenetri- ,liquid; alkylenepolya minel from the group consisting of amine, and hexamethylenediamine until a substantially uii'degraded native cellulose fiber of reducedr erystallinity is produced, impregnating said treated fibers with a ureaformaldehyde resin, andYthenI-drying the impregnated vfi fl I -1, v

RefereneesCited in the fileofthis patent UNITED STATES PATENIS I FOREIGNPATENTS 479,341 j Great Britain Feb. 3, 1938 OTHER REFERENCES Trogus et al.:'Zeitschrift fiir Physikalische Chemie, vol. 14-B, 1931, pp. 387-4595. 

